Werner's Syndrome (WS) is a rare autosomal recessive disorder which resembles premature aging and may provide an important model of senescence in humans. WS results in the early development of diabetes, cataracts, atherosclerosis, neoplasms and osteoporosis. ThUs, the discovery of the gene for WS may provide important insights into the mechanism of the most common diseases associated with aging. Fibroblasts from WS patients demonstrate a markedly reduced replicative lifespan and growth rate compared to fibroblasts from age matched controls. Replicative potential normally declines in an age-related fashion, and the growth rate of fibroblasts in culture from normal elderly subjects closely resembles that of young WS patients. We hypothesize that a mutation in the WS gene on chromosome 8 results in the pathology observed in Werner's syndrome. The experiments described in this project are designed to identify and characterize the WS gene. Based on the now substantial number of disease genes which have been recently identified by a positional cloning strategy, the overall approach of this proposal is positional cloning in order to identify a pool of candidate genes from the region, followed by analysis of the candidate genes in order to isolate the causative mutation. The studies in this research project will use novel, powerful methods such as cDNA selection for the identification of expressed sequences, and single stranded conformational polymorphism analysis for mutation detection. The broad, long term objective of this proposal is to investigate the functional aspects of the Werner's syndrome gene mutation possibly by complementation assay or studies in knockout mice. These studies may offer new insights into the critical regulatory steps of aging at the cellular level.